Grooved brake discs. Which way?

[nomis36]

I’ve just ordered some drilled and grooved disks for my car. They haven’t arrived yet but I thought I’d google which way the grooves should be ready for the install this weekend. It seems there’s a lot of conflicted opinion on this. Assuming they’ve got straight vanes, should the grooves lean towards the front or rear or does it not matter?
Even suppliers that have posted videos on YouTube seem to contradict each other!

[steve_n]

Doesn't matter. What does matter is the internal vanes direction if they are curved. Only really expensive discs tend to use curved vanes.

https://www.zeckhausen.com/catalog/index.php?cPath...

[E-bmw]

As above if curved internal castings.

If not and assuming the grooves are different left to right the normal way I believe is such that the grooves sweep the pad surface inside to out on the disc face.

[d_a_n1979]

nomis36 said:

I’ve just ordered some drilled and grooved disks for my car. They haven’t arrived yet but I thought I’d google which way the grooves should be ready for the install this weekend. It seems there’s a lot of conflicted opinion on this. Assuming they’ve got straight vanes, should the grooves lean towards the front or rear or does it not matter?
Even suppliers that have posted videos on YouTube seem to contradict each other!

The zeckhausen link above is your guide...

Just fitted these Brembo's to my touring; this is the way they sit - no silly noises, braking is superb as is the initial bite etc




There's different schools of thought when it comes to the direction of them, and there wasn't a direction instruction in the box so I went for my preferred.

I will see how they go; but they performed superbly up to The Highlands on Sunday and back yesterday

[steve_n]

The above pictures are further confirmation it doesn't matter, the grooves are all the same direction and therefore come out different on each side.

[nomis36]

steve_n said:

The above pictures are further confirmation it doesn't matter, the grooves are all the same direction and therefore come out different on each side.

Oh yeah, I didn’t notice that at first. Thanks.

[nomis36]

d_a_n1979 said:

The zeckhausen link above is your guide...

Just fitted these Brembo's to my touring; this is the way they sit - no silly noises, braking is superb as is the initial bite etc




There's different schools of thought when it comes to the direction of them, and there wasn't a direction instruction in the box so I went for my preferred.

I will see how they go; but they performed superbly up to The Highlands on Sunday and back yesterday

That’s reassuring to hear. I was a bit concerned they are going to be noisy. I can live with that under heavy braking as long as they are silent under normal use. Thanks.

[E-bmw]

steve_n said:

The above pictures are further confirmation it doesn't matter, the grooves are all the same direction and therefore come out different on each side.

With those ones, yes you are obviously correct.

Although I have bought grooved discs that were "sided" and had reversed grooves such that both would either be in-to-out, or out-to-in and the instructions that came with those ones said they should be fitted as I said above.

However that could have been also because the ventilation castings were curved also, I would expect that if there was a right & wrong way it would be covered by instructions with the discs.

[E-bmw]

nomis36 said:

d_a_n1979 said:

The zeckhausen link above is your guide...

Just fitted these Brembo's to my touring; this is the way they sit - no silly noises, braking is superb as is the initial bite etc




There's different schools of thought when it comes to the direction of them, and there wasn't a direction instruction in the box so I went for my preferred.

I will see how they go; but they performed superbly up to The Highlands on Sunday and back yesterday

That’s reassuring to hear. I was a bit concerned they are going to be noisy. I can live with that under heavy braking as long as they are silent under normal use. Thanks.

They shouldn't be any noisier that plain discs.

[d_a_n1979]

E-bmw said:

nomis36 said:

d_a_n1979 said:

The zeckhausen link above is your guide...

Just fitted these Brembo's to my touring; this is the way they sit - no silly noises, braking is superb as is the initial bite etc




There's different schools of thought when it comes to the direction of them, and there wasn't a direction instruction in the box so I went for my preferred.

I will see how they go; but they performed superbly up to The Highlands on Sunday and back yesterday

That’s reassuring to hear. I was a bit concerned they are going to be noisy. I can live with that under heavy braking as long as they are silent under normal use. Thanks.

They shouldn't be any noisier that plain discs.

There will be some noise; simple physics, but it's not noticeable, more so once they're all bedded in properly (which you must ensure you do)

I've had grooved, C Hook and ATE "Powerdiscs' and they've all been very quiet; the C Hook were the noisiest of the lot

[nomis36]

E-bmw said:

With those ones, yes you are obviously correct.

Although I have bought grooved discs that were "sided" and had reversed grooves such that both would either be in-to-out, or out-to-in and the instructions that came with those ones said they should be fitted as I said above.

However that could have been also because the ventilation castings were curved also, I would expect that if there was a right & wrong way it would be covered by instructions with the discs.

I think the ones I’ve ordered are facing the same way when fitted. Like you say, if it was important I would like to think they’d say so in the instructions and the very fact people on the internet/YouTube can’t agree confirms it’s not important. To my mind having the grooves leaning backwards so in to out looks more logical.

[nomis36]

d_a_n1979 said:

There will be some noise; simple physics, but it's not noticeable, more so once they're all bedded in properly (which you must ensure you do)

I've had grooved, C Hook and ATE "Powerdiscs' and they've all been very quiet; the C Hook were the noisiest of the lot

And there’s the next debate…. Bedding in/burnishing. There’s a lot of conflicting opinions on that too! I’ve always just driven the car for half an hour doing gentle slow downs but avoided stopping if possible. I watch a video the other day saying you should break hard from 60 to 20 repeatedly around 10 times getting the brakes very hot and smokey! Doesn’t sound like good practice to me but is it???

[d_a_n1979]

nomis36 said:

d_a_n1979 said:

There will be some noise; simple physics, but it's not noticeable, more so once they're all bedded in properly (which you must ensure you do)

I've had grooved, C Hook and ATE "Powerdiscs' and they've all been very quiet; the C Hook were the noisiest of the lot

And there’s the next debate…. Bedding in/burnishing. There’s a lot of conflicting opinions on that too! I’ve always just driven the car for half an hour doing gentle slow downs but avoided stopping if possible. I watch a video the other day saying you should break hard from 60 to 20 repeatedly around 10 times getting the brakes very hot and smokey! Doesn’t sound like good practice to me but is it???

I don't go that OTT - but I do normal driving and then when on a clear bit of bypass; some 70-30 runs, not overly hard on the brakes, but enough to get them warm and then 5-10mins of normal driving after that to let them cool down normally and then they're usually fine after that

It just helps clear any crud off the discs/pads after the initial braking and gets the contact surfaces 'in sync' if that makes sense?